Medical research in India suggests that baby girls are much more likely to die than infant boys, even from illnesses that can be treated.

The research, published in the British Medical Journal, was carried out at St Stephen's Hospital in Delhi.

The report concludes that the imbalance in the proportion of deaths may be due to the fact that baby girls are less welcome and are treated less favourably by parents.

India has an unusual gender balance.

In most countries, women slightly outnumber men, but in the year 2001, for every 1,000 male babies born in India, there were just 933 girls.

This has often been explained by the fact that some Indian mothers abort their female offspring because they regard them less favourably than boys.

Unexplained deaths

But the latest research suggests that discrimination may persist into childhood.

The researchers analysed autopsy reports of babies in three socially deprived parts of Delhi over a five-year period and discovered that the overall death rate for girls was almost one-third higher than that for boys.

This was particularly the case for sudden, unexplained deaths - three out of four cases were girls.

The researchers suggest that some of these deaths may be cases of parents actually killing their female babies.

Where death occurred because of a severe and non-preventable disease, there was no gender gap, but deaths due to diarrhoea - which is treatable - were twice as likely to happen to girls as to boys.

Again, the researchers suggest that this could be due to discrimination, with parents seeking medical help more urgently for male than for female offspring.

Dr Amod Kumar, who carried out the study, said: "Girls are stronger than boys, they are more likely to survive, but somehow in this particular area, we are finding that girls are dying more of these diseases."

He said the government was taking measures to tackle the problem of discrimination.

"The supreme court has already made a law which forbids any sex determination while pregnant," Dr Kumar said.

"Several things have to be done, like ensuring that every child gets adequate medical care, no matter whether it is a girl or boy, and mortalities should be investigated properly."

Buying brides

There is evidence that the more widespread use of pre-natal checks has increased the number of female foetuses being aborted in India.

The sex ratio is so skewed in some states, men cannot find brides

In many clinics, the illegal abortion of girls is common practice.

As a result of gender prejudices, in some states the male-female ratio is now so skewed that men are running out of potential brides.

Many are resorting to "buying" girls from poor communities outside their region to bear their children.

Meanwhile, in the southern state of Tamil Nadu, human rights groups are trying to help mothers found guilty of killing female offspring, saying the women are as much the victims as the babies.

Surveys there indicate that 16 newborn girls in every 1,000 are killed.

However, daughters are not seen as a burden in every state - in north-eastern Meghalaya the daughters of local Khasi and Jaintia tribesmen inherit all their ancestral property.

Women also run family businesses, dominate the households and take all key family decisions.

But even there a challenge is being mounted to the matrilineal society, with men concerned that marriages to male outsiders are undermining property rights.